The research program/project includes the following studies: 1. Normal development of the nervous system in humans, to be carried out on the embryos and fetuses of the Carnegie Collection and on others that have been collected, and including detailed studies of: (a) the normal sequence of development of the central and peripheral nervous system, skull, vertebrae, and limbs in staged embryos, so as to provide an accurate morphological base for the analysis of congenital defects and malformations; (b) The growth and maturation of the fetal nervous system, skull, vertebrae, and limbs, especially with respect to the down-growth of tracts such as the pyramidal tract through highly organized and functioning brain stem and spinal cord. Particular attention will be paid to correlation with congenital defects and malformations. Exploratory studies on the development of human cortex on embryos and fetuses collected over the years will be continued. Volumetric and linear measurements on the spinal cord and ganglia of staged embryos, utilizing new computerized methods, are planned. 2. Normal development of the nervous system in non-human primates using the material of the Carnegie Collection and the California Primate Research Center will continue. 3. The computerized catalogue of prenatal primate material will be completed. 4. Clinicopathological studies of human congenital defects and malformations and morphological correlations with experimental studies will continue to be carried out at the UCD Medical Center in Sacramento.